Calc II Partial Fractions with Natural Logs

Click For Summary
SUMMARY

The discussion centers on solving the integral \(\int \frac{dx}{x(1+\ln x)}\) using partial fractions. The original poster attempted to express the integrand as \(\frac{A}{x} + \frac{B}{1+\ln x}\) but encountered difficulties, leading to the conclusion that partial fractions are not applicable since the integrand is not a rational function. A suggested substitution of \(u = 1 + \ln x\) was proposed as a more effective approach to solving the integral.

PREREQUISITES
  • Understanding of integral calculus
  • Familiarity with logarithmic functions
  • Knowledge of partial fraction decomposition
  • Experience with substitution methods in integration
NEXT STEPS
  • Study the method of substitution in integral calculus
  • Learn about integrals involving logarithmic functions
  • Review the limitations of partial fraction decomposition
  • Explore advanced integration techniques for non-rational functions
USEFUL FOR

Students studying calculus, particularly those struggling with integration techniques involving logarithmic functions and partial fractions.

demersal
Messages
41
Reaction score
0

Homework Statement



\int\frac{dx}{x(1+ln x)}

Homework Equations


Partial Fractions? Maybe I am solving this wrong...


The Attempt at a Solution



\frac{A}{X} + \frac{B}{1+ln x} = 1

A(1+lnx) + Bx =1
A + Alnx + Bx =1

This doesn't seem to work out properly. I have been having a lot of trouble understanding partial fractions so any help in assisting me in making this first step of the problem would be greatly appreciated! Even if partial fractions aren't the correct way to go about this, if you could explain how you knew what to do, I think it would help me a lot in the long run! Thanks!
 
Physics news on Phys.org
I don't think you can use partial fractions like that since the integrand is not a rational function.

Try a substitution, let u=1+ln x
 
let u=lnx
 
ignore me! i was sick :(
 
rocomath said:
ignore me! i was sick :(

Your sub still works too
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
Replies
9
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K